That increased risk could have enormous public health implications. A study of 16,000 people reported last year by Medco Health Solutions, a prescription drug provider, found that 39.2% of people taking Plavix and a proton pump inhibitor after implant of a stent -- an artery-opening tube -- suffered serious cardiac events, compared with 26.2% of those taking Plavix alone. The Canadian study of 13,636 people hospitalized with heart attacks between 2002 and 2007 was started as a response to basic science studies showing that the acid-lowering drugs turned off Plavix, said Dr. The full study, presented at an American Heart Association meeting, has been submitted to a. "We linked prescribing data with hospital data on these more than 13,000 patients prescribed Plavix after a heart attack and found that people on certain proton pump inhibitors had a 40% increased risk of a recurrence," said Juurlink, lead author of the report, published online in the Canadian Medical Association Journal. Proton pump inhibitors such as Prilosec and Prevacid are among the most widely prescribed drugs, and Plavix (clopidogrel) is the second highest-selling drug in the world, the researchers said. It's not the first study to find such a link.

Juurlink, head of the division of clinical pharmacology and toxicology at Sunnybrook Health Sciences Centre in Toronto.